GHSA-6qh5-m6g3-xhq6 BIT-parse-2026-33508 CVE-2026-33508

Parse Server LiveQuery subscription query depth bypass

High npm

Severity: 0.0 / 10; High · CVSS 4.0
Exploit chance (EPSS): 0.35%; Chance of exploitation in the next 30 days. Higher than 29.09% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-674 Uncontrolled Recursion
Fix: 9.6.0-alpha.45; Upgrade parse-server to this version or later

Description

Impact

Parse Server's LiveQuery component does not enforce the requestComplexity.queryDepth configuration setting when processing WebSocket subscription requests. An attacker can send a subscription with deeply nested logical operators, causing excessive recursion and CPU consumption that degrades or disrupts service availability.

Deployments are affected when the LiveQuery WebSocket endpoint is reachable by untrusted clients.

Patches

The fix adds query condition depth validation to the LiveQuery subscription handler, enforcing the same requestComplexity.queryDepth limit that already protects REST API queries.

Workarounds

There is no known workaround other than upgrading.

Affected versions

npm

Package	Vulnerable	Fixed in
parse-server	`>= 9.0.0, < 9.6.0-alpha.45`	`9.6.0-alpha.45`
parse-server	`< 8.6.56`	`8.6.56`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

parse-server npm → `9.6.0-alpha.45`

npm

npm install parse-server@9.6.0-alpha.45

yarn

yarn add parse-server@9.6.0-alpha.45

pnpm

pnpm add parse-server@9.6.0-alpha.45

Severity breakdown

CVSS 4.0 0.0

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Attack vector: Network
Attack complexity: Low
Attack requirements: Present
Privileges required: None
User interaction: None
Confidentiality (vulnerable system): None
Integrity (vulnerable system): None
Availability (vulnerable system): High
Confidentiality (subsequent systems): None
Integrity (subsequent systems): None
Availability (subsequent systems): None

CVSS 3.1 7.5

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Weakness

CWE-674: Uncontrolled Recursion

The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.

How to prevent it

Implementation: Ensure that an end condition will be reached under all logic conditions. The end condition may include checking against the depth of recursion and exiting with an error if the recursion goes too deep. The complexity of the end condition contributes to the effectiveness of this action.
Implementation: Increase the stack size.

References

Advisories

nvd.nist.gov/vuln/detail/CVE-2026-33508

Packages

github.com/parse-community/parse-server

Timeline

Mar 20, 2026 Published
Jun 17, 2026 Last updated by the source
Oct 31, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-r899-h629-j84r Parse Server vulnerable to stored XSS via malformed Content-Type bypassing file upload extension blocklist	Low	Also affects parse-server
GHSA-97pr-9hgg-3p8r parse-server: LiveQuery discloses object data to a subscriber across an ACL read-access change	Low	Also affects parse-server
GHSA-v8x7-r927-cc93 parse-server: Stored XSS via non-standard file extension bypassing file upload extension blocklist	Low	Also affects parse-server
GHSA-cgxm-vr2f-6fj8 parse-server: Denial of service via exponential-time processing of deeply nested query operators	High	Also affects parse-server
GHSA-wmwx-jr2p-4j4r parse-server: Relation `$relatedTo` query bypasses `protectedFields` and owning-object ACL	Medium	Also affects parse-server
GHSA-75v4-m273-5j49 parse-server: Endpoints `/login` and `/verifyPassword` disclose MFA secrets and protected fields when `_User` get is denied	Medium	Also affects parse-server
GHSA-7wqv-xjf3-x35v parse-server: Stored XSS via trailing-dot filename bypassing file upload extension blocklist	Low	Also affects parse-server
GHSA-p84r-h6rx-f2xr parse-server: Server option routeAllowList is bypassable through batch sub-requests	Medium	Also affects parse-server

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